The Northern Border pipeline system links supply in Western Canada with major markets in the Midwest, including Chicago.

Connecting from the Canadian Mainline at the Saskatchewan-Montana border, the Northern Border System transports natural gas along 2,265 km (1,407 miles) of pipeline southeast through Montana, North Dakota, South Dakota, Minnesota, Iowa to Chicago, Illinois. There are access points to Midwest markets through multiple interconnects.

In fact, about 17 per cent of the gas imported into the United States from Canada in 2008 was carried on the Northern Border pipeline.

The Northern Border System is eyeing expansion to sources of Rockies gas through the Bison pipeline project which is in development. The Bison pipeline project will involve the construction of approximately 486 km (302 mi) of pipeline that will extend northeastward from the Dead Horse region in Wyoming to interconnect with the Northern Border pipeline in Morton County, North Dakota. From there, natural gas will be transported on Northern Border to Midwest markets.

The Northern Border System is part of TransCanada's network of 57,000 km (35,500 mi.) of wholly owned and 11,500 km (7,000 mi.) of partially owned natural gas pipelines connecting major supply basins with major markets all across North America. TransCanada is one of the continent's largest providers of gas storage and related services with approximately 380 Bcf of storage capacity - that's the second largest in North America. In total, TransCanada delivers approximately 20 per cent of the natural gas consumed in North America each day.

TransCanada operates and effectively owns 16.7 per cent of the system through its 33.3 per cent interest in TC PipeLines, LP.